1. Field of the Invention
The present invention relates to a collaboration system in which collaborative work is performed by using a plurality of computers connected to a network.
2. Related Art
Input/output and data processing operations can be synchronized among a plurality of computers connected to each other through a network to enable a common image to be displayed on the displays of the plurality of computers or to enable an input to one of the computers to be reflected in the other computers. Today, collaboration systems which use this technique and in which a plurality of users use a plurality of computers and perform collaborative work by displaying a common work screen image on the displays of the computers are coming into widespread use.
As an example of this kind of collaboration system, a system such as Lotus Sametime from IBM-Lotus is known in which a screen image to be displayed on the displays of computers is exchanged in the form of a bitmap image among the computers under the control of an application program to display a common screen image on the computers.
Another conventional art is a Web collaboration system in which information on operations on a Web browser is transmitted and received between computers to display the same Web page on the computers (see, for example, Japan Published Unexamined Patent Application 10-124461). As this kind of Web collaboration system, there have been further proposed a system in which a computer operated by a user obtains a Hyper Text Markup Language (HTML) file through the medium of a proxy server (collaboration server) and displays a Web page, and in which a notice of a page transition in one computer is sent to other computers to display the same Web pages on the computers (see, for example, Japan Published Unexamined Patent Application 2001-51932), and a system in which an anchor tag is embedded in an HTML file cached by a proxy server to enable identification of any place on a Web page displayed on each of computers (see, for example, Japan Published Unexamined Patent Application 2002-149640).
Further, a technique to assist communication among users participating in collaborative work by combining these collaboration systems with a so-called chat system in which text data input to one of computers is displayed on the other computers to hold a conversation in a real-time manner has been proposed (see, for example, Japan Published Unexamined Patent Application 2003-150527).
As described above, various propositions have been made with respect to collaboration systems for assisting collaborative work performed by a plurality of users using a plurality of computers interconnected through a network.
However, the conventional collaboration techniques have problems such as those described below.
In the system in which a display screen image is transmitted and received in the form of a bitmap image to display a common screen image on a plurality of computers, the amount of data communicated as image data to be transmitted and received is large and the load on the network in traffic is increased.
Also, since a bitmap image is used, displayed images vary depending on the display size and the resolution of the displays of computers. When an image is displayed on computers, there is a possibility of an edge portion of the image lying off-screen on certain ones of the computers, while the whole of the image is displayed on the other computers. Thus, there is a possibility of hindrance to collaborative work.
FIG. 20 is a diagram showing an example of display of a work screen image on displays having different resolutions in the conventional art in which a bitmap image for a work screen image is exchanged among computers.
Referring to FIG. 20, in a case where a particular point in a work screen image displayed on a high-resolution terminal A (indicated by a star-like symbol ★ in FIG. 20) is determined as an attention point, the position of the attention point is out of the display area of the work screen image in display of the work screen image on a low-resolution terminal B. In this case, it is difficult to locate the point in the work screen image to which attention is directed in collaborative work.
Further, in this system, processing dependent on an operating system (OS) is required to obtain a display screen image. Therefore, only limited kinds of OSs are usable in computers utilizing the collaboration system.
In the collaboration systems described in the above-mentioned Japan Published Unexamined Patent Applications 10-124461 and 2001-51932, a Web page is used as a display screen image and only information on operations on a Web browser may be communicated among computers, so that the communication traffic load is reduced. Also in display of an image, the Web browser is operated (by scrolling or the like) to enable the entire image to be visually recognized independently of the display size of the displays of the computers.
However, it is necessary that the computers in these systems use a common Web browser or compatible Web browsers in order to enable each of operations such as input operations on a display screen image on one of the computers based on a Web page to be reflected in the display screen images on the other computers. For this reason, only limited kinds of Web browsers and OSs are usable.
Also, if only a web page is displayed as a display screen image, it is difficult to clearly show to users participating in collaborative work to which portion of the display screen image a predetermined one of the users is paying attention.
In the system described in Japan Published Unexamined Patent Application 2002-149640, an anchor tag is embedded in an HTML file to identify any place on a display screen image (Web page) without any Web browser and OS dependences. A pointer used in collaborative work can be displayed in the identified place and scrolling of the Web browser screen image can be controlled so that the identified place is displayed.
However, this conventional art uses a stationary anchor tag embedded in an HTML file as a reference mark to perform pointer display control and Web browser scroll control. It is, therefore, necessary to prepare in each user terminal computer an application program for informing other computers of synchronization points in pointer display and screen image scrolling, and an environment in which the application program is executed. Therefore there are cases where the function provided by the system described in Japan Published Unexamined Patent Application 2002-149640 for synchronization of pointer display and screen image scrolling cannot be used, while a display screen image based on a Web page can be displayed.
In the conventional art described in Japan Published Unexamined Patent Application 2003-150527, a chat system is combined with a collaboration system to realize assistance to communication among users.
In this conventional art, however, communication between a collaboration server and user terminals is performed in the same manner as communication in other collaboration systems and, therefore, the same problem as that with one of the arts described in the previously-mentioned patent documents, i.e., the problem that only limited kinds of Web browser and OSs are usable or the problem that an execution environment for performing synchronization of the pointer display positions and screen image scrolling by using an anchor tag as a reference mark is required, still remains.